As this type of technique, heretofore, there is a fluid control valve 100 disclosed in Patent Document 1 listed below and shown in FIG. 11.
As shown in FIG. 11, the fluid control valve 100 is provided with a valve chamber 113 in which a first passage 121 and a second passage 122 are communicated with each other. Further, those first and second passages 121 and 122 are communicated respectively with tubes not shown for supplying a fluid. A valve seat 115 is formed around a valve hole through which the valve chamber 113 is connected to the first passage 121. Further, a diaphragm valve element 104 is provided to come into or out of contact with the valve seat 115. The first passage 121 includes a port communication passage 121a and a valve-hole communication passage 121b. The first passage 121 and the second passage 122 are connected with each other at a right angle in the fluid control valve 100. A connecting part between the port communication passage 121a and the valve-hole communication passage 121b includes a valve seat wall portion 125 under the valve seat 115.
A fluid flowing in the first passage 121 through the tube passes through the valve chamber 113 and then flows in the second passage 122.